One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,5)(4,6)(7,8)(9,10,13,16)(11,14,17,21)(12,15,20,24)(18,22,19,23)(25,26,31,28)(27,34,29,32)(30,36,38,33)(35,39,37,40)(1,2,4,6)(3,5,8,7)(11,17)(14,21)(18,19)(22,23)(25,26,31,28)(27,32,29,34)(30,33,38,36)(35,39,37,40)(9,11)(10,14)(12,18)(13,17)(15,22)(16,21)(19,20)(23,24)(25,27,31,29)(26,32,28,34)(30,35,38,37)(33,39,36,40)(9,10)(11,14)(12,15)(13,16)(17,21)(18,22)(19,23)(20,24)(25,28,31,26)(27,32,29,34)(30,36,38,33)(35,39,37,40)(1,2)(3,7)(4,6)(5,8)(9,11)(10,14)(12,19)(13,17)(15,23)(16,21)(18,20)(22,24)(25,29,31,27)(26,32,28,34)(30,37,38,35)(33,39,36,40)(1,3,4,8)(2,5,6,7)(9,12)(10,15)(11,18)(13,20)(14,22)(16,24)(17,19)(21,23)(25,30)(26,33)(27,35)(28,36)(29,37)(31,38)(32,39)(34,40)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.